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Friday, 3 June 2016

RTL on HF? no way!


I read with interest an article in Practical Wireless from June 2016 describing a neat looking receive converter to be placed up front of an RTL dongle type receiver.

These RTL devices are easy to find for a few GBP:

Here's the schematic of the converter:

And its built on a PCB from OHS Park which cost a staggering $5 USD for 3 including postage to the UK. They were delivered in a very timely manner too! 

You will see that I have actually built two - but basically we have a 50MHz oscillator and a mixer, so in the example below my SDR would be tuned to 70MHz and I would be listening to my signal generator on 20MHz. The output contains what you would expect from a mixer in that we have the input frequency, the on board oscillator frequency, their sum, their difference and all the other harmonics from this mixing process:

More to follow once I have it up and running with the RTL dongle, but so far so good!

Local conditions.


  1. Hi, mark, it is vu3zmv again.
    please see the no hardware patch in link below.

    i am using this. you can please analyse its performance.
    . Incidntally if you own any rtl sdr with R820T2, the performance could be better.
    However with a small pre amp at input, we get same performance.
    all the best for all the wonderful lab experiments you are conducting and I feel as if i am in your lab too while reading your articles.

  2. Hi mark. I was very interested in your blog RTL on HF.
    Unfortunally, i can 't find more info to the article on
    Practical Wireless or other source. I have build several HF converters, link on my site 'on1bes' . Please, have you a name of the autor in the P.W. magazine, or a copy of the article ?
    regards, on1bes

    1. its in June 2016 and the author is Jemnny List G7CKF